U.S. Pat. Nos. 3,848,033 and 3,996,639 to Callahan, et al. describe an aggregate having a spherical or semi-spherical shape, a void center and a single cavity in the external surface communicating to the void center prepared by
(a) preparing a slurry, the slurry comprising a suspending liquid and distinct particles of a first solid suspended in said liquid; PA1 (b) preparing a particle bed consisting of particles of a second solid; PA1 (c) forming droplets of the slurry; and PA1 (d) dropping the droplets of the slurry into the particle bed in such a manner that the total droplet is not immersed in the powder and under conditions where the suspending liquid is at least partially removed from the slurry droplet to form an aggregate of the distinct particles of the first solid. PA1 (a) preparing a slurry, the slurry comprising a suspending liquid and distinct particles of a first solid suspended in said liquid; PA1 (b) preparing a particle bed consisting of particles of a second solid; PA1 (c) forming droplets of the slurry; PA1 (d) dropping the droplets of the slurry into the particle bed under conditions where the suspending liquid is not immersed in the particle bed; PA1 (e) removing at least part of the suspending liquid from the slurry droplets under conditions so as to impart a differential rate of drying between the external surface of the slurry droplets and the interior of the droplets, wherein prior to removing at least part of the suspending liquid from the slurry droplets, the slurry droplets are subjected to means sufficient to (1) enhance the rate of drying on the external surface of the slurry droplets and to (2) retard the rate of drying in the interior of the slurry droplets, whereby aggregates having a void center and two cavities 180.degree. apart in the external surface of said aggregates communicating to the void center are produced upon removal of at least part of the suspending liquid from the slurry droplets. PA1 (a) diffusion predominantly normal to liquid flow and PA1 (b) convection predominantly in the direction of the liquid flow. When the amphora particles described in U.S. Pat. No. 3,848,033 are employed in a trickle-bed reactor, both (a) and (b) apply to the outer surface but (a) predominates in the interior of each particle. However, the geometry of the amphora II of the present invention opens up the interior of the particles to convective mass transfer and the reactor approaches plug flow behavior. Improved hydrogen utilization and/or higher conversions of desired product is appreciated in the hydrotreating or hydrocracking processes using the amphora II particles since more external surface of said particles is exposed to the moving film. The moving liquid decreases the rate of coke build-up in the interior of the amphora and therefore the effective lifetime of the catalyst is enhanced. PA1 (a) dispensing droplets of an aqueous slurry onto a hydrophilic bed and heating either from above or below said aqueous slurry in the presence of an undirectional stream of air, or PA1 (b) dispensing droplets of an aqueous slurry onto a hydrophobic bed and heating from above said aqueous slurry. PA1 (1) freezing the slurry droplets prior to application of heat, PA1 (2) utilizing a slurry with a relatively low solids content, preferably from 5 to 50 percent by weight, PA1 (3) utilizing a gelatinous slurry, and PA1 (4) using as a suspending liquid a mixture of water and liquid of similar polarity having a higher boiling point than water, such as an alcohol or a polyalcohol.
Using the process disclosed in the above patents, rounded aggregates are formed which are highly attrition resistant. In certain applications, the invention described therein is capable of producing a rounded aggregate having a void center. Those aggregates having a void center and a single cavity in the external surface communicating to the void center have been named "amphora." These amphora are especially desirable for catalysts because the exposed outer surface of the aggregates is substantially increased as compared to the surface of a pellet prepared by normal compaction techniques. The catalyst particles of the present invention, hereinafter referred to as "amphora II," are especially advantageous for processes in which the feed is only partially vaporized, i.e., trickle-bed processes. The particles have substantially the same amphora shape described in U.S. Pat. Nos. 3,966,639 and 3,848,033 but the novel aspect of the present invention is incorporation of a second cavity 180.degree. to the first cavity, both communicating to a common void center. When amphora particles, such as those described in the above patents are employed in a trickle-bed process, the amphora which are orientated with their opening toward the top of the reactor become filled with a pool of liquid. This liquid will have a longer hold-up time than the liquid passing over the outer portion of the catalyst. If the linear velocity of the feed is sufficiently high, there should be a reasonable rate of exchange of this liquid with fresh feed, and therefore the interior of the amphora particle will still remain effective. At low linear velocities, however, the turnover rate of this liquid pool will be slow and the interior of the amphora will be filled with a stagnant or semi-stagnant liquid which will decrease effectiveness of the catalyst. The improved amphora aggregates of the present invention eliminate several problems encountered using prior art catalysts. The incorporation of the second opening in the amphora 180.degree. from the first cavity provides a means by which a liquid can pass unhindered through the void center of the amphora.
U.S. Pat. No. 3,957,627 discloses hydrotreating a hydrocarbon feed stock containing compounds with carbon-sulfur bonds, carbon-nitrogen bonds and carbon-oxygen bonds by contacting the hydrocarbon feed stock with hydrogen and a hydrotreating catalyst to remove sulfur, nitrogen and oxygen from the hydrocarbon feed stock using an amphora catalyst. West German Provisional Pat. No. 2,540,637 and Belgium Pat. No. 833,639 disclose use of amphora shaped catalysts in naphtha reforming.
U.S. Pat. No. 3,340,180 discloses a process for hydrogen treatment of heavy petroleum hydrocarbons in the presence of a catalyst comprising essentially a minor amount of a hydrogenation catalyst composited with a major amount of an activated alumina having less than 5% of its pore volume that is in the form of pores having a radius of 0-300 A. and pores larger than 100 A. radius and having less than 10% of said pore volume in pores larger than 80 A. radius. The activated alumina is prepared by treating a substance which is predominantly composed of a crystalline alumina hydrate containing from 1.2-2.6 moles of water of hydration and which is substantially free of alumina monohydrate and alumina trihydrate; the alumina hydrate being prepared by precipitation from a solution of an aluminum compound at a pH between 7 and 12, a drying to the above-mentioned water of hydration content prior to substantial transformation to an alumina hydrate having a higher or lower water of hydration content. The dried alumina hydrate is then hydrothermally treated by heating it in the presence of water in an autoclave at a temperature sufficient to vaporize the water and under the pressure generated in the autoclave at the temperature. This is followed by drying and calcining the hydrothermally treated alumina hydrate to provide the activated alumina. U.S. Pat. No. 3,764,565 discloses that a resid hydrocarbon is converted to lower boiling hydrocarbons and/or desulfurized by contacting, in the presence of hydrogen, said resid with a bed of catalyst particles comprising a catalytically active composition comprising a hydrogenation metallic component of Group VIB and/or VIII of the Periodic Table supported on an inorganic cracking matrix, wherein the catalyst particle is characterized by having a predetermined size and configuration such that the particle has a surface-to-volume ratio ranging between about 100 and about 250 (1/inches), and wherein substantially all points within the particle are less than about 0.015 inch from the particle surface.
The hydrotreating of hydrocarbon feed stocks containing carbon-sulfur bonds, carbon-nitrogen bonds and/or carbon-oxygen bonds, is well known in the art. See for example G. C. A. Schuit and B. C. Gates, A.I.Ch.E.J. 19 (3), 419 (1973); S. C. Schuman and H. Shalit, Catal. Rev. 4 (2), 245 (1970). As can be seen from the art, these reactions normally involve the use of catalysts consisting of support material impregnated with various catalytically active ingredients. Alternatively, the active ingredients and support are prepared together.
Molten solutions have been frozen by dropping a melt into a bed of small particles, see for example U.S. Pat. Nos. 3,070,837; 3,255,036; and 2,938,233. Such solidification has been carried out with the purpose of coating the pellet formed with the particles in the bed or the incorporation of large quantities of particles of the bed into the final pellet. All these techniques of the art require that the material solidified be molten.
The present invention is the result of a search for more efficient and desirable catalysts useful in the conversion of hydrocarbons.